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ANTI-INDUCTION DEVICE.

' Patented Oct. 18,- 1887 INVENTOI? Jamar C'lzrran fim BY ATTORNEYUNITED STATES PATENT OFFICE.

JAMES CURRAN, OF PORTLAND, OREGON.

ANTI-INDUCTION DEVICE.-

' SPECIFICATION forming part of Letters Patent No, 371,555, datedOctober 18, 1887.

Serial No. 234,673. (No model.)

To all whom it may concern.-

Be it known that I, JAMES CURRAN, a citizen of the United States,residing in Portland, in the county of 'Multnomah and State of Oregon,have invented certain new and useful Improvements in Anti-InductionDevices; and I do hereby declare that the following is a full, clear,and exact description of my invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

My invention is especially designed for use at the central office of atelephone-exchange; and its object is to counteract wholly or in partthe effects of currents induced by electriclight or power currents.

To this end it consists, broadly, in providing means whereby theconnection between any two subscribers lines can be made by means of aloop which is exposed to the influence of the same disturbing source asthat which affects the telephone-circuit. The loop is furnished with aswitch for presenting the polarity of the loop in opposition to thatwhich is induced on the telephone-circuit, and also with a secondswitch, which regulates the influence of the loop by connecting itssides through a variable resistance or joining them directly, and soshort-circuiting thelarger portion of the loop. I

The loop may be excited by being exposed to the disturbing influenceeither under the same conditions as the telephone-wires themselves or byforming the secondary of an induction-coil of which the primary iseither a part of the original disturbing-circuit or a wire stronglyinfluenced by it.

The construction in which my invention is embodied is illustrated in theaccompanying drawings, in which- Figure 1 shows a diagram of my circuitsand apparatus, and Fig. 2 illustrates a modified arrangement.

Referring to the drawings by letter, A is a switchboard in the centraloffice of a telephone-exchange. 1, 2, 3, 4, 5, and 6 are telephone wiresconnected to the said switchboard. 15 is a wire carrying a powerfulcurrent for the purposes of electric light or power. The wire 1 runs fora considerable distance in close proximity to the wire 15, and by reasonof its proximity has induced in it a current which afiects injuriouslythe working of the line. The wires 2, 3, 4, 5, and6 also run parallel tothe wire 15 and are inj uriously affected in different degrees,according to their distance from the disturbing-wire. Another series ofwires, 7, 8, 9, 10, 11, and 12, pass to theswitchboard A from such adirection as to be practically unaffected by the current on the wire 15.

If, now, I connect the wire 1 directly through the switch-board with thewire 10, communication by telephone through the circuit thus made willbe subject to the well-known disturbances caused by induced currents. Toobviate this I introduce between the two lines to be connected a loop,13 14, the said loop being provided with the usual plugs and flexiblecords for making connection at the switchboard. I run the loop along inproximity to the wire 15, and thus subject it to substantially the sameconditions as affect the telephone-wires 1 2 3 4 5 6. Having run thewire for a considerable distance, as described, I turn it away from thewire 15 and lead it back by a quiet route to the central office. I findin practice that by inserting a loop arranged as described between twotelephone-lines and opposing the polarity of the loop to that induced inthe telephone-circuit by the disturbing source I reduce greatly theinjurious efl'ects of the induced current. It is of course necessary toprovide apparatus for presenting the loop with different polarities toline. Accordingly I locate in a convenient position a fourpoint switch,B, having the well-understood connections for reversing the polarity. Ialso place in the loop-circuit a second switch, 0, and a series ofresistances, D. By means of the switch 0 and theresistances I canregulate the influence of the loop. More or less resistance will beincluded in the loop-circuit, according as the switch-arm is turned tothe left or right. If the switch is turned over on the stop E, the majorpart of the loop will be short-circuited. An operator can manipulate theswitches B and 0 according to circumstances to meet the various needs oftelephone service. If he is to connect two undisturbed,

lines, the switch 0 will be turned to thestop E, or the connection willbe made through the switch-board in the ordinary manner.

In Fig. 2 I have shown the wire 15 forming IOG the primary of aninduction-coil and the loop 13 and 14 "forming the secondary thereof.This may be found advantageous where it is possible to bring in the wirecarrying heavy currents and make it form the primary of an induction-coil, as illustrated. In many cases this would not bepracticable, and, in general, I prefer the arrangement illustrated inFig. l. I do not wish, however, to limit myself to that arrangement. Nordo I wish to confine myself to the use of my anti induction device inconnection with telephone-lines alone. It may be used advantageously inordi nary telegraphic service, although I expect to apply it chiefly tothe use I have described.

Having now described my invention, what I claim is l. The combination,with a telephonic or telegraphic circuit and a disturbing-line ininductive proximity thereto, of a loop exposed to the influence of thesame disturbingline, and means for connecting up the loop in thetelephonic or telegraphic circuit, the said loop containingpole'changing devices, as and for the purpose set forth.

2. The combination, with a telephonic or telegraphic circuit and adisturbing-line in inductive proximity thereto, of a loop exposed to theinfluence of the same disturbing-line, and means for connecting up theloop in the telephonic or telegraphic circuit, the said loop containingpole-changing devices and an adjustable resistance, as and for thepurpose set forth.

3. The combination, with a number of telephonic circuits and one or moredisturbinglines in inductive proximity thereto, of a loop exposed to theinfluence of the same disturbing line or lines, the said loop beingprovided with means for making connection between any two of thetelephonic circuits, as and for the purpose set forth.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

JAMES OUR'RAN.

Witnesses:

Guns. N. WAIT, M. J. DUFFY.

